four-o'clock family vs genus Pisonia

four-o'clock family and genus Pisonia both are nouns.

Word	Noun	Adjective	Verb	Adverb
four-o'clock family	Yes	No	No	No
genus Pisonia	Yes	No	No	No

four-o'clock family (noun)	genus Pisonia (noun)
a family of flowering plants of the order Caryophyllales	genus of often thorny tropical trees and shrubs and some vines; mainly America